A camera module has a problem when a foreign object (trash, dust) intrudes into a region for storing an image pick-up element of the camera module. Recent improvement in image pick-up elements to be able to capturing a higher-resolution image has made the image pick-up elements more vulnerable to such an intruding foreign object, so that, even if a minor foreign object (having a particle size of about 20 μm to 30 μm, for example) is adhered to a light receiving section of the image pick-up element, a micro lens, and the like, a shadow of the foreign object is appeared on an imaging screen as a black spot or a stain. This leads to reduction in image quality. Such a minor foreign object may not be removed because the foreign object catches on asperities of the micro lens. In addition, it may be difficult to detect the foreign object in the camera module at the time of examination, depending on where the foreign object is adhered. These situations are greatly problematic. Therefore, it is important for the camera module not to allow a foreign object (trash, dust) to intrude into the region for storing the image pick-up element of the camera module.
However, it is necessary for the camera module to have an opening for allowing light to pass through the opening into the camera module. In view of this, Patent Literatures 1 to 4 each disclose a technique for sealing an opening with use of a transparent member.
Patent Literature 1 discloses that an ultraviolet curing adhesive is applied to a whole circumference of a top surface section of a package, and the package and a cover glass (transparent member) are fixedly attached to each other.
Patent Literature 2 discloses a method for (i) bringing a pedestal mount and a cover glass (transparent member) into contact with each other via a plurality of ribs formed on the pedestal mount, (ii) positioning the pedestal mount and the cover glass, and then (iii) applying the adhesive to a semilunar cut-out section formed in the pedestal mount. The adhesive applied to the cut-out section is flowed into a whole circumference of the pedestal mount by capillary action. In this way, the pedestal mount and the cover glass are fixedly attached to each other.
Patent Literature 3 discloses a method for adhering a rim-like member and a glass cap to each other by forming a groove in a part of a ring-like adhesive section of the rim-like member, adhering an adhesive to the ring-like adhesive section other than the groove, and placing the glass cap (transparent member) onto the adhesive.
Patent Literature 4 discloses a pedestal which includes abutting sections on respective four corners of a glass cover (transparent member) mounting surface of the pedestal, and a method for adhering the pedestal and the glass cover to each other so that the abutting sections do not allow an adhesive to flowed into an imaging area when the adhesive is applied to adhesive sections.